Explore Great Basin National Park with a lifelong caving enthusiast who is “fascinated with the unknown” – and perhaps get bitten by the same caving bug that she did.

Every year, about 30,000 visitors tour the Lehman Caves beneath Great Basin National Park, near the border of Nevada and Utah.

Great Basin – est 1986

Nevada

some text

Gretchen Brown, ecologist

Read more about BBC Travel’s celebration of the US National Park Service’s 100th Anniversary.

During their half-mile underground journey, people are amazed at the dizzying array of spectacular cave features, from the usual stalactites and stalagmites to bizarre formations like frostwork, moonmilk, parachute shields and rock draperies, all of which seem like inventions from a Dr Seuss storybook.

But according to Great Basin ecologist Gretchen Brown, tourists often miss out on the other spectacular show that is happening all around them: a science fiction collection of creepy crawly critters specifically adapted to life in these caves – with some considered “new to science”.

A lifelong caving enthusiast who is “fascinated with the unknown”, Brown has been working as an ecologist at Great Basin for the past 15 years. In that time, she has tracked and catalogued such species as the rhagidid mite, the pseudoscorpion, translucent millipedes and newly resurgent long-eared bats. “One of the most exciting things in the world is to see cave predation in action!” Brown exclaimed, referencing a battle she witnessed between a pseudoscorpion and a nearly microscopic cave fly.

It’s this attention to detail that Brown encourages visitors to embrace on their trip to the park. She calls Lehman an “intimate” cave, with twists and turns that put people right in the middle of everything. Watching a tiny drip of water inch its way down a small soda straw opening in the ceiling is to witness the magic of geology in action, she said. And when the tour stops, instead of snapping pictures of the rock towers, she recommends kneeling down to take a look at the cave floor. Perhaps you’ll see a wiggling centipede darting into a hole. Or maybe even spot a “minden” nest of a native packrat, a home passed down through hundreds of generations of mouse families – that is, if one isn’t too sensitive to dig into fossilized mouse poop.

Even with precautions, the near endless procession of visitors brings a certain amount of unintended external dust and dirt to the caves, clogging and coating the floors and walls with visitor “lint”. During Great Basin’s “Lint Camp”, volunteers are assigned a few square feet to meticulously clean off the above-ground coating. Brown’s amazement at the clean sections is akin to art historians restoring a masterpiece painting to its original form – a Sistine Chapel of speleological features. And as a special reward, volunteers are allowed entry into sections of the cave usually reserved for park staff.

For those who are willing to dig even deeper into Great Basin’s secrets, a “wild cave” awaits – one without tours, trails, lighting or guides. Not for the claustrophobic, visitors must apply for a permit, bring their own safety equipment, attest to previous caving experience and demonstrate their ability to squirm through a narrow opening in a sample cave section made out of concrete in front of the visitors centre. Brown describes the 1,000ft-long “Little Muddy” cave as “kind of maze-y”. When asked if people often get lost inside it, she responds with a bit of caver Zen: “You’re never lost as long you’re enjoying where you are.”

Brown clearly enjoys where she is, exploring both the above- and below-ground ecosystems at Great Basin National Park. She encourages visitors to do the same, and perhaps get bitten by the same caving bug that she did (metaphorically at least, considering those centipedes). Above ground, Brown boasts of the park’s equally lively flora and fauna populating the high desert environment, from the yapping kit foxes to the 5,000-year-old Bristlecone pine trees, one of the oldest living things on Earth. And at night, far from any city lights, the high elevation and dry air provide one of the best places in America to view stars. The dome above, of course, is only rivalled by that which lies below.

If you liked this story, sign up for the weekly bbc.com features newsletter, called “If You Only Read 6 Things This Week”. A handpicked selection of stories from BBC Future, Earth, Culture, Capital, Travel and Autos, delivered to your inbox every Friday.